500,000-Gallon R.O. Plant #2 Elevated Steel Tank

Assessment Report

Assessment Date

April 20, 2018

Prepared for: Mount Pleasant Waterworks

Allan Clum Operations Manager

Prepared by: AECOM

425 South Cashua Drive Florence, South Carolina 29501

Certified By: Stephen Ryan Cox

NACE Certified Coating Inspector Level 3 Cert. No. 48451

Contents

1.0 General Information ......................................................................................................... 3

2.0 Summary of Field Observations........................................................................................ 4

2.1 Exterior ................................................................................................................... 4 2.2 Interior .................................................................................................................... 4 2.3 Concrete Base ..........................................................................................................4 2.4 Lead Results ............................................................................................................ 4

3.0 Recommendations........................................................................................................... 5

3.1 Exterior .................................................................................................................. 5 3.2 Interior .................................................................................................................... 5 3.3 Concrete ................................................................................................................. 6

3.4 General Repairs ........................................................................................................6

Appendices Appendix A Assessment Report Appendix B Inspection Photos

1.0 General Information The R.O. Plant #2 Steel Tank is a 500,000-gallon elevated water tank built by Brown Steel in 1990. The tank is located onsite of the RO #2 Plant. The site is near the intersection of Mathis Ferry Road and 7th Avenue. The tank is located in an established residential subdivision and is on the backside of a Medical Center. At the request of Mount Pleasant Waterworks, AECOM conducted an assessment of the tank on April 20, 2018.

The purpose of the assessment was to evaluate the current condition of the tank coatings and repair needs, and provide recommendations for corrective actions to address any issues found during the assessment.

2.0 Summary of Field Observations

The coating on the exterior of the tank is in very poor to poor condition. The overall adhesion on the tank is poor to fair. There is minor to moderate mildew, chalking, and moderate to heavy cracking present on the exterior surface. Corrosion and some related pitting on the interior surface was observed during the assessment. Most of the corrosion visible was present above the water line. Other areas of corrosion were observed below the water line, but could not be inspected closely due to the tank being full and in service. There were numerous antennas located on the tank balcony and handrails. These will need to be removed before renovation begins, and alternative methods for mounting these antennas will be necessary to inhibit galvanic corrosion after renovation is complete. Installing a corral on the top of the tank may be a better solution. Lastly, the column ladder was in poor to severe condition. 50% of the ladder rungs have a metal loss of 50% or greater. Ladder connections and bolts are also severely corroded.

2.1 Exterior There are minor to moderate areas of corrosion on the exterior, including but not limited to the exterior balcony floor and handrails, roof panels, column and dome ladder, etc. The exterior coating has minor to moderate cracking. Dry film thickness of the current coating ranges from 17-24 mils with an average of 20.5 mils. With the minor to moderate corrosion areas, poor adhesion, and excessive coating thickness, AECOM recommends the exterior of the tank receive a full blast and a four coat exterior coating system.

2.2 Interior The interior of the tank has corrosion around the seams, access hatch, overflow pipe, painters ring, sidewall sheets, roof beams, and vent. There is surface rust across 20% of the roof of this tank with rust breakthrough occurring in isolated areas on the remaining 80% of the tank. Below the water line there are various areas of isolated corrosion on the sidewalls of the tank. The bottom of the tank and riser could not be inspected because the tank was full of water during the inspection. There was a moderate amount of sediment in the bottom bowl of the tank. AECOM recommends the tank interior receive a full blast and three coat interior system at the same time the exterior is renovated.

2.3 Concrete Base The concrete base is showing minor cracking and appears to be coated with same product used on the exterior of the tank. AECOM recommends that the concrete base be coated with a two coat epoxy at the next renovation. Once epoxy is cured, apply a 2” layer of modified aliphatic polyaspartic between concrete base and base plate.

2.4 Lead Results Basic lead tests were conducted on the exterior of the tank during the assessment. There were no indications of lead on the tank. Pictures were taken during testing.

3.0 Recommendations

3.1 Exterior The exterior of the tank had poor to moderate adhesion. With the existing coating system thickness at an average of 20.5, and the moderate to heavy cracking present, this tank would not be a good candidate for an overcoat. To address these issues properly, the existing exterior coating system should be fully removed, and be blasted to a SSPC SP6 Commercial Blast standard, minimum 2.5 profile.

Specific recommendations are as follows:

Surface Prep – Pressure wash exterior of tank with 5000+ PSI pressure washer with a rotating nozzle to remove salt and other contaminants prior to blasting(SSPC-SP1). Crew must pressure wash tank daily prior to blasting and painting.

Prime Coat- Apply one (1) full coat of aromatic urethane, (performance equal to Tnemec Series 91 h20 or 94 h20 HYDRO-ZINC) at 2.5-3.0 dry mils.(Sacrificial Coating)

Stripe Coat Apply one (1) full coat of polyamidoamine epoxy (performance equal to Tnemec Series 69) at 3.0-5.0 dry mils.

Intermediate Coat Apply one (1) full coat of aliphatic acrylic polyurethane (performance equal to Tnemec Series73 ENDURA-SHIELD) at 2.5-3.0 dry mils.

Finish Coat - Apply one (1) full coat of advanced thermoset solution fluoropolymer (performance equal to Tnemec Series 700 HYDROFLON) at 2.5-3.0 dry mils surface profile.

3.2 Interior There was moderate to minor corrosion noted during the assessment. AECOM recommends that the tank be blasted to a SSPC SP10 near-white blast on the interior. Repairing and repainting the interior, while repairing and repainting the exterior, typically adds a significant cost savings for construction, and puts both surfaces on the same future rehab schedule. Once surface prep is approved, a three-coat NSF-approved interior liner should be applied. All roof beams, painters ring, and roof laps should be coated with an NSF-approved caulk.

Specific recommendations are as follows:

Surface Prep: Use SSPC SP10, near-white blast. Prime Coat: Apply zinc-enriched urethane (performance equal to 94h20 HYDRO-

ZINC) at 2.5-3.0 dry mils. (Sacrificial Coating)

Stripe Coat: Apply polyamidoamine epoxy (performance equal to Tnemec N140 POTA-POX PLUS) at 4.0-6.0 dry mils.

Intermediate Coat: Apply polyamidoamine epoxy (performance equal to Tnemec N140 POTA-POX PLUS) at 4.0-6.0 dry mils.

Finish Coat: Apply polyamidoamine epoxy (performance equal to Tnemec N140 POTA-POX PLUS) at 4.0-6.0 dry mils.

Caulking: Caulk Sikaflex 1a or equivalent on roof beams, seams, and painter’s ring. 3.3 Concrete The concrete base should be coated during the renovation to guard against future deterioration. Once surface prep is approved, a two-coat epoxy system should be applied to the concrete base. The gap between the base plate and concrete base is void of grout and should be caulked. Once caulk is cured, a 2-inch wide layer of modified aliphatic polyaspartic should be applied between the concrete base and base plate to provide a moisture barrier.

Specific recommendations are as follows:

Surface Prep: Pressure wash with 5,000 PSI pressure washer with rotating nozzle. Fill any voids with non-shrink grout.

Prime Coat: Apply polyamide epoxy (performance equal to Tnemec 69 HI BUILD EPOXOLINE II) at 4.0-8.0 dry mils.

Finish Coat: Apply polyamide epoxy (performance equal to Tnemec 69 HI BUILD EPOXOLINE II) at 4.0-8.0 dry mils.

Caulking: Caulk with Sikaflex 1a or equivalent between base plate and concrete.

Additional Coat: Apply modified aliphatic polyaspartic (performance equal to Tnemec 256 EXCELLATHANE) 50.0-80.00 DFT mils.

3.4 General Repairs Additional repair recommendations are as follows:

1. Complete all repair work before intermediate coat of paint is applied unless indicated otherwise.

2. Remove existing riser manway and install a new 30” bolted manway with davit arm or

with hinges. 3. Power wash, clean, and coat concrete footing. Paint footings after final tank exterior

coating is applied. Fill any cracks with non-shrink grout.

4. Remove existing vent screen, cap, and pipe and replace with new aluminum tank vent. Install one (1) new 30” Diameter vent, pipe, and flange. Seal weld to the tank. Provide a minimum of 10” clearance between the top of the tank and the bottom of the flange.

5. Install three (3) 2” W x 36” H pipe for existing antennas mounted to the magnetic boards

attached to the roof. Remove antenna form the magnetic boards and attach antenna to the new installed pipes.

6. After interior intermediate coat is applied, seal all weld joints, overlapping plates, etc.

above the high water level with an NSF approved sealer. Use Sikaflex-1a or approved equal.

7. Weld two, 4” x 1”x1” angle iron vertically to support new name plate. Provide new name

plate with all pertinent information.

8. Install pressure gauge at base on riser of tank. Confirm location of pressure gauge with Owner.

9. Install ¼” x 4”H x 6” L flat bar at 10’ OC on columns, side wall and roof. Relocate

antenna cables and conduit and attach to the flat bar installed.

10. If desired, remove existing target board and all associated hardware including cables, float, and target board structure. Seal weld cable penetration with ¼” x 4” x 4” plate on interior and exterior.

11. (Interior and Exterior Ladders) Provide 3/8" diameter, stainless steel cable, 10,000

pound test, as manufactured by DBI Industries, or equal, attached to the face of the ladder at the top and bottom. Provide stainless steel cable stays at 20'-0" maximum spacing.

12. Drill 25-30 drain holes at minimum ¾” on the balcony floor, and the floor has moderate

pitting in various areas.

13. Remove exterior ladder and install approximately 130’ ladder. Ladder side rails shall be minimum 3/8” x 2 ½” flat bar with 16” clear spacing. Rungs to be minimum ¾” diameter slip resistance spaced at 12” on center. All rungs shall be seal welded to the side rails on both inside and outside. Ladder shall meet OSHA requirements.

14. Remove all antenna cables and brackets for the handrail and catwalk. Install corral on

the exterior roof and relocate all antennas and cables.

15. Install four (4) penetration holes with kick-plate on the catwalk floor.

16. Remove all antenna messenger pipes and metal bands mounted to the front side of the columns and relocate messenger pipes to the inside of the columns.

17. Existing tree branches will need to be trimmed back approximately 20’ to allow for

containment, and prevent further mildew and damage to new coating.

Probable Cost of Construction

3.5 Estimated Costs

Cost estimates are provided for the recommendations identified in Section 3. These represent budget level cost estimates based upon current market conditions and do not incorporate any considerations for impacts of future inflation. Table 4.1 presents the estimated costs for long term recommendations to be implemented as soon as funds are available.

Table 4-1. Estimated Costs for Long Term Recommendations

Treatment Location Surface

Prep

Coating System Expected

life cycle

Cost

Full Blast Wet Interior SSPC SP10 AUZR, MPE, MPE 15+ years $70,000

Containment/Full

Blast

Exterior SSPC-SP6

AUZR,PE,AAP, ATSF 15+ years $160,000

Repair Items $70,000

Contingency (~15%) $45,000

Containment $100,000

Total Estimated Costs $445,00

APPENDIX A ASSESSMENT REPORT

Date: April 20th , 2018 AECOM Project No.: 60559635

Water System: Mount Pleasant Waterworks

Tank Name: R.O. #2 Elevated Steel Tank

Tank Location: 375 7th Avenue, Mount Pleasant SC

Nearest Intersection: Mathis Ferry Road & 7th Avenue

Latitude/Longitude: N: 32.8080 W: - 79.8909 Tank Description: Capacity: 500,000 gallons Erection Date: 1990 Manufacturer: Brown Steel Design Type: Elevated Number of Columns: 6 Column Diameter: 36” Riser Diameter: 60” Riser Manhole Size: 18” Height to Overflow: Verify at renovation Construction Type (welded or riveted): Welded Security: Secured fence with barb wire.

Foundation Conditions:

Condition of concrete: Structure Good. Minor areas of cracking. Fill

with non-shrink grout prior to coating.

Coating Fair to Good. Minor isolated areas of coating delaminating. Coating applied to the top of the concrete base.

Condition of base plate: Structure

Good. Isolated areas of minor rust. Some anchor bolts have moderate corrosion.

Coating Good. Isolated areas with minor corrosion.

Condition of grout: Structure Fair to Good

Coating Fair to Good.

Foundation Conditions: Is caulking required around base plates: Yes.

Tank Exterior Conditions:

Condition of top of tank:

Structure Good

Coating Poor to Fair. Isolated areas with minor to moderate corrosion. The coating has minor to moderate cracking.

Condition of vertical shell plates:

Structure Good

Coating Very Poor to Poor Isolated areas with minor to moderate surface corrosion. Moderate chalking and cracking.

Condition of Riser: Structure Good.

Coating Fair to Good. Minor to moderate chalking. Isolated areas of corrosion. Moderate cracking.

Condition of Radial Rods:

Structure Poor to Fair minor to moderate corrosion.

Coating Fair to Poor. Moderate isolated areas of corrosion and mildew. Various areas or coating delamination.

Condition of Columns:

Structure Good.

Coating

Poor to Fair. There are isolated areas of corrosion. One column has metal bands installed which are creating moderate corrosion between the column and bands. Minor mildew present. Minor cracking present.

Condition of Bottom of Tank: Structure Good.

Coating Poor to Fair. Moderate corrosion present. Moderate mildew present. Moderate cracking present.

Condition of Balcony: Structure Very Poor to Poor. Balcony floor plates have moderate to major corrosion.

Tank Exterior Conditions:

Coating Various areas of corrosion and low lying areas that are holding water.

Overflow, Vent and Roof Hatch:

Condition of overflow pipe: Structure Good.

Coating Fair to Good. Isolated areas of corrosion.

Overflow pipe diameter: 10”.

Location of overflow pipe: Attached to column

Type of sanitary protection at overflow outlet: Flapper/Screen combination

Condition of overflow outlet: Structure Good

Coating Good

Vent: Structure

Very Poor to Poor. Outdated style vent. Replace with 30” Frost Free Proof vent. Heavily corroded.

Coating Very Poor to Poor

Diameter: ~24” ID Square

Does it have a screen? Yes.

Roof hatch: Structure Fair. Install a 30” square hatch.

Coating Fair to Good. Minor corrosion present.

Size: 24” x 24” Rectangle

Does it have a curb? Yes

Is roof hatch locked: Yes.

Exterior Ladders:

Column: Structure Very Poor to Poor. Severe corrosion

present and needs to be replaced.

Coating Very Poor to Poor. Severe to Moderate coating delamination and corrosion.

Roof: Structure Fair to Good. Secured to top of tank.

Tank Exterior Conditions:

Coating Fair to Good. Various areas of corrosion.

Safety Climb Equipment:

Column: Cable safety climb is installed. Very Poor Condition. Replace during rehab.

Roof: Cable safety climb is installed. Very Poor Condition. Replace during rehab.

Obstruction Lights and Logo: Does the tank have obstruction lights: No Condition of obstruction lights: N/A Sign text: Mount Pleasant and (Tree) See Photos Sign height, and location: Verify at next renovation. Tank Interior Conditions:

Condition of roof plates:

Structure Fair to Good. Not inspected thoroughly inspected due to tank in service.

Coating

Poor to Fair. Numerous areas of corrosion break through is occurring in the roof. Less than 20% of the interior roof is surface rust with isolated areas of breakthrough beginning in the remaining 80%.

Condition of roof beams:

Structure

Poor to Fair. Areas of previous corrosion are evident. Roof beam structure is scab welded to the roof plates, with the majority of the corrosion occurring at weld seams and top of beams.

Coating

Fair to Good. Isolated areas of rust bleed occurring at weld seams and from top of beams. Caulk all weld seams and roof structure at renovation.

Condition of vertical plates: Structure Good.

Coating Fair to Good. Isolated areas of minor corrosion. Isolated areas of pitting occurring.

Tank Interior Conditions:

Condition of bottom plates: Unable to inspect due to tank having water during inspection. Moderate sediment was present.

Condition of ladders: Structure Fair

Coating Fair. Various areas of coating failure resulting in moderate corrosion.

Condition of safety climb equipment: Safety climb is not installed on interior. Install new stainless steel cable climb at renovation.

Condition of painter’s rail: Structure Unable to inspect due to tank being

in service at time of inspection.

Coating Unable to inspect due to tank being in service at time of inspection.

Was tank empty when inspected: No

Was there any accumulated sediment in the bottom of the tank?

Yes, minor to moderate amount of sediment is present in the tank.

APPENDIX B INSPECTION PHOTOS

RO #2 Plant Elevated Tank Photos

Photos Taken By: Ryan Cox

04/20/18

Adhesion Test on Column Adhesion Test on Column

Column and Site Riser and Site

Column and Site Riser and Column

Riser and Column Column and Overflow

Column and Overflow Overflow Outlet

Column and Overflow Column and Overflow

Tank Belly, Column, and Struts Overflow Flapper Valve

Overflow Outlet Screen Concrete Base, Base Plate

Old Adhesion Test Column, Concrete Base, Base Plate

Column Tank Belly

Riser Manhole, Concrete Base Name Plate

Riser Manhole Riser

Riser and Tank Belly Riser, Horizontal Rods, and Tank Belly

Tank Belly and Horizontal Rods Tank Belly and Horizontal Rods

Tank Belly and Horizontal Rods Column

Column Column

Column Radial Rods

Column Column

Column, Struts, and Radial Rods Column, Struts, and Radial Rods

Concrete Base, Base Plate, and Anchor Bolts Anchor Bolts, Base Plate, Missing Grout

Antenna Bands on Column Antenna Bands on Column

Antenna Bands on Column Concrete Base, Base Plate

Antenna Mount with Barrier Antenna Mount with Barrier

Antenna Mount with Barrier Antenna Mount with Barrier

Radial Rod Radial Rods and Column

Riser, Column, Tank Belly Riser and Concrete Base

Riser Riser

Column and Radial Rods Concrete Base and Base Plate

Concrete Base and Base Plate Adhesion Test on Column

Adhesion Test on Column Lead Test(Indicated No Lead Present)

Column Ladder Connection Column Ladder Connection

Column Ladder Column and Strut

Strut and Radial Rod Strut and Radial Rod

Strut and Radial Rod Strut and Radial Rod

Struts, Radial Rods, and Column Struts, Radial Rods, and Column

Struts, Radial Rods, and Column Struts, Radial Rods, and Column

Struts and Radial Rods Column Ladder Connection

Column Ladder Step Column Ladder Connection

Column Ladder Step Column Ladder Step

Column Ladder Step Column Ladder Steps

Column Ladder Step Column Ladder Step

Column Ladder Strut and Radial Rods

Struts Tank Belly and Radial Rods

Column and Tank Belly Column Ladder

Column and Radial Rods Riser and Tank Belly

Tank Belly and Horizontal Rods Tank Belly and Horizontal Rods

Tank Belly and Horizontal Rods Tank Belly and Horizontal Rods

Column Ladder Column Ladder

Balcony Floor Interior Access Hatch

Balcony and Handrail Column Ladder

Balcony Floor Vertical Shell Plates

Balcony Floor Balcony Floor

Balcony and Handrail Vertical Shell Plates

Balcony and Handrail Handrail and Target Board

Target Board Balcony Floor

Target Board Heavy Cracking in Vertical Shell Plates

Moderate Cracking in Vertical Shell Plates Moderate Cracking in Vertical Shell Plates

Moderate Cracking in Vertical Shell Plates Balcony Floor

Moderate Cracking in Vertical Shell Plates Balcony Floor

Balcony Floor Mild Cracking in Vertical Shell Plates

Vertical Shell Plates and Target Board Roof Ladder

Roof Ladder Balcony and Handrail

Vertical Shell Plates Balcony Floor

Balcony and Handrail Vertical Shell Plates, Logo

Column Moderate Cracking on Vertical Shell Plates

Handrail, Galvanic Corrosion Balcony and Handrail

Vertical Shell Plates Balcony and Handrails

Balcony Floor Balcony Floor, Column

Vertical Shell Plates Balcony Floor

Balcony and Vertical Shell Plates Balcony and Vertical Shell Plates

Balcony and Handrails Balcony Floor

Vertical Shell Plates Vertical Shell Plates

Vertical Shell Plates Vertical Shell Plates and Column

Balcony Floor Vertical Shell Plates

Vertical Shell Plates, Logo Handrail, Galvanic Corrosion

Overflow Pipe Tank Penetration Overflow Penetration in Balcony Floor

Overflow Penetration in Balcony Floor Overflow Pipe Tank Penetration

Overflow Pipe Tank Penetration Balcony Floor

Moderate cracking on Vertical Shell Plates Moderate cracking on Vertical Shell Plates

Moderate cracking on Vertical Shell Plates Adhesion test attempt (Could not make a straight cut due to cracking)

Adhesion Test on Exterior Vertical Shell plates Moderate cracking on Vertical Shell Plates

Vent Vent

Vent and Antenna Mount Vent and Screen

Vent and Antenna Mount Roof and Penetration Cap

Tank Roof and Target Board Tank Vent and Antenna Cable

Tank Vent Tank Vent

Tank Vent Tank Vent

Tank Roof/Top of Vent Tank Roof/Top of Vent

Roof and Penetration Cap Roof

Roof and Penetration Cap Roof

Roof Roof Ladder

Roof Ladder Roof

Surrounding Area Surrounding Area

Surrounding Area Surrounding Area

Surrounding Area Surrounding Area

Vent Base Tank Roof

Interior Roof Beams and Float Penetration Interior Overflow Outlet

Interior Roof Beams Interior Roof Beams

Interior Roof Beams Interior Roof and Vent Penetration

Interior Roof and Overflow Outlet Interior Roof and Overflow Outlet

Interior Roof Beams Interior Float for Target Board

Interior Belly Sediment Interior Belly Sediment

Interior Belly Sediment Interior Belly Sediment

Interior Belly Sediment Interior Belly Sediment

Interior Vertical Plates Interior Roof Beams

Interior Roof Beams Interior Roof Beams

Roof Hatch Locked Roof Hatch Locked

Roof Hatch Target Board

Balcony Floor Balcony Floor

Balcony Floor

Overall View

Overall View

Overall View

Overall View

Overall View

Overall View Overall View